In printing systems, and especially in roll-to-roll printing systems, in which printed sheet output from the system is gathered by winding the sheet onto a take-up roll, there is always the issue of managing the work-flow from the printing system when the take-up roll is full, i.e. when it reaches its maximum sheet-carrying capacity. At that time, it becomes necessary to replace the full take-up roll at the output end of the printing system, which typically requires a manual intervention by a system operator. If the printing continues, the printed sheet may be collected in a buffer until the new take-up roll is installed and ready for taking-up (e.g. winding up) the printed sheet. The time required for a manual intervention by an operator in this regard is typically several minutes. In this time, the printed sheet in the buffer can become creased or damaged and, if too much time is required by the operator, the printing system must be temporarily interrupted, which has a significant negative impact upon system productivity, as well as on the print quality of the printed sheet after re-starting the printing.
In EP0135662 A2 a continuous paper web, unwound from a feeding roll, is severed into sheets of the desired length. From the severing station, the web is advanced to a winding station, to which cardboard cores supported at their ends by two idle mandrels are also supplied. The winding station is defined by two endless belts diverging from each other in the direction of the outlet from this station and moved at different speeds.
At the inlet of the winding station, the cardboard cores are rotated by said belts, whereby the length of paper web advanced to said station by the lower belt is wound onto one of said cores. The so-formed roll is transferred to a discharge station, where it is released by disengaging the mandrels from the ends thereof. The two free mandrels are then transferred to a loading station where they pick up a new cardboard core. Drawbacks of the device in EP0135662 A2 are that it is relatively complex, large, and costly.